Exam QUIZ 7 PHYSICS 2B SPRING 2010
Name_Professor S. K. Sinha __________________________________
µ = 4. . 10^-7 = 1.26 . 10^-6 N/A2
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Figure 30.1
1) In Figure 30.1, a wire and a 10 ohm resistor are used to form a circuit in the shape of a square, 20 cm by 20 cm.
A uniform but non-steady magnetic field is directed into the plane of the circuit. The magnitude of the
magnetic field is decreased from 0.90 T to 0.30 T in a time interval of 60 ms. The average induced current and
its direction through the resistor, in this time interval, are closest to:
A) 40 mA, from a to b
B) 40 mA, from b to a
C) 60 mA, from a to b
D) 24 mA, from b to a
E) 24 mA, from a to b
Figure 30.4
Wire is wound on a square frame, 30 cm by 30 cm, to form a coil of 4 turns. The frame is mounted on a horizontal shaft
through its center (perpendicular to the plane of the diagram). The coil is in clockwise rotation, with a period of 0.01 s. A
uniform, horizontal, magnetic field of 0.80 T is present. At a given instant, the plane of the coil forms a 60° angle with the
horizontal, as shown.
2) In Figure 30.4, at that instant, the emf induced in the coil is closest to:
A) 11 V
B) 18 V
C) 16 V
1
D) 9 V
E) 13 V
Figure 30.5
3) In Figure 30.5, a coil of wire is placed on the axis of a solenoid carrying a DC current. Which of the following
will NOT result in an EMF being induced in the coil?
A) Move the coil toward point P.
B) Rotate the coil about the z-axis.
C) Rotate the coil about the y-axis.
D) Rotate the coil about the x-axis.
E) Change the current in the solenoid.
Situation 31.1
An 18 mH solenoid inductor is wound on a form 0.80 m in length and 0.10 m in diameter. A coil is tightly wound around the
solenoid at its center. The coil resistance is 5.0 ohms. The mutual inductance of the coil and solenoid is 60 µH. At a given
instant, the current in the solenoid is 300 mA, and is decreasing at the rate of 2.5 A/s.
4) In Situation 31.1, at the given instant, the induced emf in the solenoid is closest to:
A) 45 mV
B) 30 mV
C) 35 mV
2
D) 40 mV
E) 50 mV